text:
Why can the A-10’s engines flame out merely from ingesting smoke from its gun?
Apparently, firing the A-10’s GAU-8 cannon can sometimes cause its GE CF34 engines to flame out from ingesting the smoke from said gun.
It’s easy to see how the gun’s smoke could be ingested by the engines:

(Image by 67blackcherry at The Gear Page, via @Koyovis here at avSE.)
Even when the gun is firing and its smoke is blowing into the engines, though, the vast majority of what’s going into the intakes is still air; even though it is true that, to quote Wikipedia, "[g]un exhaust is essentially oxygen-free", this exhaust is immediately forced into (and diluted by) ambient air the moment it leaves the barrel, and is blown back towards the engines (and diluted still further) by yet more air.  And modern high-bypass turbofans like the CF34 are - indeed, have to be - designed to keep running even when quite a considerable proportion of the incoming air is not, in fact, air (I think I remember reading somewhere about small high-bypass turbofans being tested, successfully, for their ability to keep running when given a half-and-half mix of air and rainwater, although it’s possible that I might be misremembering).  So how can gunsmoke ingestion be enough to flame out the A-10’s engines?

That's because its smoke is so badass. The only thing tougher than A-10 gun smoke, is Chuck Norris cigarette smoke.

I found a 1955 NACA research memorandum entitled "STALL AND FLAME-OUT RESULTING FROM FIRING OF ARMAMENT", specifically looking at flameouts in the F-86, F-94, and other aircraft associated with the firing of guns or rockets (especially in the case of the F-94, which had a nose-mounted rocket pod).  While the analysis in the paper does concern itself with a high speed (Mach 0.9) and high altitude (45,000 ft) scenario, I think that we can reasonable interpret its results for the A-10.
The paper points to the following factors following, from the aircraft firing a weapon, which could lead to an engine flameout:
(1) Increased inlet temperature
(2) Changed inlet pressure
(3) Distorted inlet-pressure and temperature profiles
(4) Entry of combustibles into engine
(5) Reduced oxygen content in gases entering engine
Of all of these, the first item was noted as the most significant, and the first step in the chain of events that results in reduced oxygen in the combustor, or, if you'd like it stated another way, an increased fuel-air ratio.  Since the exhaust gas from the gun is much hotter than ambient (anecdotally, the gas block of an AR-15 can hit up to 600 deg F after firing 600+ rounds, so I'd imagine the barrels of the GAU-8 would be at least that) and does not cool completely before entering the engine, the engine has to deal with its effects -- and the first stage to see it (ignoring the fan) is the compressor.
The compressor of a jet engine is, essentially, a fan, but one that spins fast enough to compress the air coming into the engine such that you can burn fuel in the combustor and push the maximum amount of gas as quickly as possible out the back of the engine.  However, in order to operate, the combustor needs a low enough fuel-air ratio to allow combustion (i.e., enough air to burn the fuel it's dumping in).  Similarly, the combustor is a fan, made up of a series of airfoils -- if these airfoils stall, the combustor doesn't work anymore...again resulting in too little oxygen in the combustor to allow for combustion.
Considering inlet temperature first, we can think about it from a gas-law point of view.  If I heat a volume of air, its density will decrease.  Hence, if I'm taking the same volume of air into my engine and compressing it, I'm taking in significantly less oxygen on a per-molecule basis.  If I take the ideal gas law as a rough estimate and double the temperature, my density is cut in half -- so now my engine has access to half the air.  According to the NACA study (and your picture), gun gases typically spread out in front of the aircraft, leading to a greater heating effect in the surrounding air, even if that is more spread out.  Between this and a momentum exchange between the gun gas and the ambient air, as the gun exhaust is slowed by the still, ambient air, the NACA study found that firing four 20 mm cannon reduced the inlet pressure to their study aircraft (an F-94, I believe) by as much as 9%.
So, this is a lot of hand-waving, so let's look at the effect all this on the jet engine in the NACA study.  The temperature increase on the plot is an inlet temperature increase -- and it doesn't take much of a temperature rise to significant decrease the mass flow rate of air through the engine...and stall the compressor.

Compressor stalls can also occur due to distorted inlet air velocity profiles (a fan is typically designed for air to come in axially and uniformly), another side effect of exhaust gases non-uniformly mixing with the inlet air.  Similarly, if burning particulate matter is ingested, this could change the velocity profile inside of the compressor itself by artificially decreasing the pressure ratio across the compressor.  Naturally, if combustion is delayed until the combustor, these particles will have little effect.
You can also look at this from the perspective of the downstream effect of having less air moving through the engine, or the fuel-air ratio in the combustor.  This could also be affected by a decrease in the available oxygen in the gun gases as well.

As we can see, though, changes in inlet temperature in the compressor appears to be the more sensitive parameter for this particular engine.  As mentioned in the NACA report:

The increase in compressor-inlet temperature during armament firing
  is probably the most important single factor affecting engine performance. This increase in temperature is sufficient by itself to account
  for the observed occurrences of compressor stall and flame-out.

Hence, according to this article, the final solution to the A-10's problem (while gun gas deflectors and the like were considered) was a reformulation of the propellant used in its shells and the addition of a link between the gun trigger and the engine ignition system.

As an anecdote, I remember reading that a similar thing happened with the Su-25, the Soviet equivalent of the A-10, when firing large rockets (S-24s) from the inner pylons. I don't have a robust source for this, sadly.


text:
What requirements are needed to fly an approach that requires you to fly over the US/Mexico border?
I was flying North of El Paso Texas listening to El Paso Approach when I heard Approach ask a Falcon Jet if they could fly into Mexico to fly a Runway 4 GPS approach.  At El Paso, the runway 4 approaches require you to fly across the US/Mexico border into Mexico.  What requirements are needed to fly an instrument approach that requires you to fly over Mexico?  Would you require a radio telephone permit to use the radio even though you are talking to an FAA controller?

Related: How is US Class B airspace enforced in Canada?

I had flown my plane (small 4-seater) from Houston to California a few years ago and on the way back, I stopped in El Paso to refuel and sleep for the night.  While in contact with the tower, following whatever vectors they were giving me, I noticed that I was about to cross into Mexico.  It's pretty obvious from the style of buildings and how close they are together that one area is Mexico and the other area is the US, especially at 1000 ft (or less) AGL.  I asked the controller if this was correct since it would put me across the border into Mexico.  I seem to remember him saying something about they had an agreement with Mexico that allowed them to use / control that airspace.

Aircraft registered in some countries may not be able to overfly other countries without first obtaining a permit or meeting other requirements.
FDC NOTAMS are informative in this regard. Some time ago I was operating an aircraft registered in Europe, flying from Canada to the UK. The planned route crossed northern Maine. I had flown this route lots of times with Canadian-registered aircraft, no problem there. Look at the requirements of FDC 6/4255 (A0006/16) - which is current right now -
ZZZ SECURITY - C. CIVIL AIRCRAFT REGISTERED IN CANADA, MEXICO, BAHAMAS, BERMUDA,
CAYMAN ISLANDS , OR THE BRITISH VIRGIN ISLANDS WITH A MAXIMUM
CERTIFICATED TAKEOFF GROSS WEIGHT OF 100,309 POUNDS (45,500 KGS) OR
LESS ARE AUTHORIZED TO TRANSIT U.S. TERRITORIAL AIRSPACE IF IN
COMPLIANCE WITH etc. etc.

With the Europe-registered aircraft, we didn't fall into one of those categories, so were not authorized to transit US airspace, and had to detour slightly to the north to remain in canadian airspace at all times. Had we been US or Canadian-registered, we could have crossed over Maine without issue. (We could have requested an overflight permit, but that would have delayed us more than we wanted). ATC did try to clear us over Maine, but we had to refuse.
Interestingly, there are quite a few examples of airspace near a lot of countries' borders where flight over one country is controlled by ATC of the other country. ATC will happily keep you separated from other aircraft, but a clearance by them is just for that purpose. Their clearance does not imply overflight permission - that is normally the State Department's / CBP purview.
It is possible that Mexico also imposes certain requirements for overflying aircraft - always worth checking.
Also, the aircraft insurance policy may impose restrictions on what countries' airspace can be overflown.

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text:
Why did the propellers not fail to the feathered position in the Atlantic Southeast Airlines Flight 2311 Crash?
In the ASA Flight 2311 crash the failure of a quill resulted in the loss of propeller pitch control.  The propellers ended up with a pitch angle of 3 degrees which caused reduced thrust and increased drag resulting in severe asymmetrical thrust situation.  The airplane was uncontrollable in this configuration and crashed. The propeller manufacturer, Hamilton Standard, had tested the propellers in a laboratory and had shown that the propellers will feather with a loss of pitch control.  However, a flight test orchestrated by the NTSB had shown that due to the "aerodynamic forces of flight" the propellers did not feather as designed.
My question is what exactly caused the propellers to not feather in flight when the propellers successfully feathered in the laboratory?  I am looking for a more detailed answer than "aerodynamic forces of flight".

You can find the full text of the NTSB investigation here and according to that report (bolded for emphasis),

Examinations of the left propeller components indicated a propeller
  blade angle of about 3 degrees at impact. This position was based upon
  the position of the pitchlock acme screw. The left PCU ballscrew
  position indicated that the PCU had commanded a blade angle of 79.2
  degrees. The discrepancy between the ballscrew position and the
  position of the pitchlock acme screw is a strong indication that a
  disconnect between these two components occurred prior to impact and
  that the left propeller had achieved an uncommanded blade angle below
  the normal flight range.

And later in the report

Using measurements and the inspection procedures for the quill and
  transfer tube of the Hamilton Standard Alert Service Bulletin, it was
  determined that the left PCU quill spline was worn to the extent that
  its gear teeth did not engage the transfer tube spline. In addition,
  the test cell and flight tests showed that the propeller blade angle
  could not be controlled by the PCU with a disengaged transfer tube. In
  the test cell, the blade angle moved toward high pitch; however, the
  propeller was operating at zero airspeed and did not experience normal
  flight loads. In contrast, the flight tests showed that the blade
  angle would move toward low pitch with a disengaged transfer tube. The
  blade characteristics indicate that centrifugal and aerodynamic
  twisting moments tend to move the blades toward low pitch.
The Safety
  Board believes that the worn quill on the left engine PCU became
  disengaged from the transfer tube prior to the loss of control of the
  airplane during the approach to Brunswick. Moreover, the propeller
  blades moved to a low angle, resulting in an asymmetric lift and drag
  condition that exceeded the capability of the pilots to counteract
  with the airplane controls available.

In simple terms the unit that controls the propellor pitch experienced a failure from worn out components that lead to a case where the propellor did not completely feather. The specific part seems to be the PCU quill (to answer your question directly).
Even later in the report they discuss why the failure was not really covered by the testing originally. The testing was not necessarily incorrect as much as it may have been incomplete and not foreseen this issue with the quill.

The investigation found that wear of the quill was not considered
  during the certification of the propeller system because of the very
  light torque loading on the quill during flight. Service history of
  the PCU quill prior to the introduction of the titanium-nitrided
  transfer tube indicted that quill spline wear was not a problem.
  Additionally, the manufacturer provided an analysis during
  certification indicating that even in the event of a failure, the
  propeller would either drift into the feathered position or maintain
  the blade angle present when the failure occurred. However, the
  accident involving flight 2311 and the subsequent investigation
  have determined that these assumptions, though originally supported by
  numerous engineering evaluations and manufacturing experience, are
  invalid and that there are single failure modes that could result in
  an uncommanded propeller blade angles below flight idle.

No props would drift into feather or not move when disconnected from pitch control. Even blades with counterweights have spring or oil pressure to assist them to feather because of CTM (centrifugal twisting moment) Disconnected spinning blades will go to 0 pitch.
signed, 42+ year propeller mechanic

Your answer could be improved with additional supporting information. Please [edit] to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers in the help center.

Re "No props would drift into feather... when disconnected from pitch control"-- that's a pretty broad statement.  You are basically saying that Hamilton Standard's expectations that they based on the lab tests were obviously absurd from the start.  A little more support would be good.

(Deleted last part of comment as I don't really know what propeller "pitch" is referenced to anyway.)  If 0 pitch is the opposite of "feathered", consider adding "which is the opposite of feathered." to last sentence.

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text:
What is the difference between Vno and Va
What is the difference between the maximum structural cruising speed (Vno) and the manuevering speed (Va)?  Can you also please explain how these speeds are calculated?
I do understand that Va is set to where the wing will stall before the plane will go over its G limit but what does Vno mean?

Va limits G loads resulting from pilot input of maximum control deflection to limit load.  Vno limits G loads caused by vertical gusts over 30 ft/sec, without pilot input, to limit load.
In other words, Va protects you from bending the wings from pulling too hard, and Vno protects you from bending the wings from going too fast through bumps.

I have heard Va used in reference to turbulence penetration speed not Vno.

Turbulence Penetration Speed is Vb.  Vno is Normal Operating and is similar to Vb but seems to be applied only to non-transport a/c.  Transport a/c have Va, Vb and Vmo.

It looks like my question is a duplicate of another answer found here:
Basically to summarize flying below Va guarantees that the plane will stall before exceeding the design load factor.  Vno is more like a guideline as to structural limits that may occur during normal turbulence and does not provide and real protection.


text:
Do any aircraft have liquid-cooled brakes?
Aircraft wheelbrakes, especially those on heavy aircraft, get really, really hot during landings and rejected takeoffs, and cool down very, very slowly without active cooling.  This imposes limits on how short turnaround times can be between flights, in order to avoid overheating the brakes and wearing them out (which would be bad).  To counter this, many aircraft that make frequent, short flights have brakes with forced-air cooling.
However, air, being a gas, is far from the best coolant available; do any aircraft use liquid-cooled brakes for maximum brake cooling capability?  This seems like it would be most useful for very large aircraft that make frequent short, heavily-loaded flights from short fields.

Related: How are brakes cooled on heavy aircraft? and interestingly Why do some A380 main wheels have no brakes?

A liquid heat exchanger system for brake discs, with coolant, lines, some way of transferring heat from the disc pack to the heat exchanger, that would somehow keep the entire apparatus liquid tight... yikes.  I can only imagine what a monstrosity such a design would be, even if it's technically feasible.
Brake temperature requirements don't affect gate turnaround times. 99.99% of the time you land and taxi in, and an hour later, off you go, long after they've cooled off.  On a reject, on the rare occasion the reject didn't require a return to gate for maintenance action of some kind, you have the Brake Temperature Monitoring System to tell you when the brakes are good to go even if you don't return to gate (most rejects are because of a Caution or Warning prior to V1 -  and if you reject in the "high energy" phase, usually above 80 or 90 kt, which is a callout during the roll, your airline will likely require you to return for a brake and tire inspection anyway, "liquid cooled" or not).  If the BTMS is MEL'ed, you will have to observe a minimum brake cool down time as per the associated MMEL Ops Procedure.
So yes there are times when regular brakes require you to sit and wait for a period of time, but it would happen on 1 departure in, well, thousands (departure delays from brake overheating, from pilots riding the brakes during taxi, is probably a bigger problem operationally).   In any case, in view of the actual operational impact, nobody would want to pay for such a cooling system even if it was feasible.


text:
During multiengine training, are pilots taught how to use the throttles for control?
The use of a multiengine aircraft’s throttles for steering and pitch control is critically important should the aircraft’s primary flight controls fail or severely malfunction; are pilots nowadays taught this potentially-lifesaving skill during training for a multiengine rating?

No.  In a piston multi course the focus is on flying the airplane and single engine procedures.  Loss of rudder control in something like a Seminole is not a big deal unless the engine quits after that and then you have a problem, and it's not one of controlling yaw with differential thrust.
If your rudder cables broke with both engines running you would naturally use bits of differential power to center the ball as required while flying straight, and little rudder is required to turn so that's not a big deal and you would just leave it and put up with a bit of adverse yaw. This all wouldn't require much training to figure out.
Sioux City was what you would call a freak event, with multiple simultaneous failures of flight controls for all axes, that is not catered to in design in the first place (notwithstanding the mistake, on the DC-10, of running all the hydraulic lines though one choke point; most airplanes separate control runs as much as possible to cater to turbine burst events).  They were trying to control both pitch and roll, with differential thrust to turn by skidding and by using the pitching moment of increasing/decreasing thrust to climb/descend.
No type course trains for that.  There are a million one-of-a-kind events you can dream up, which can theoretically happen, for which airliners are not certified to cope with, and where a crew might have to figure things out on the go.  If you had to train for all of them, the type course would take years to complete.


text:
Why is the Beluga chartered out for oddball missions, but not the Dreamlifter?
Both Airbus and Boeing have special outsize-cargo freighters for transporting large pieces of airliner; Airbus has five Belugas (derived from the A300), while Boeing uses four Dreamlifters (extensively-rebuilt 747s).  The Beluga fleet is primarily used for moving pieces of Airbus aircraft around, but Airbus also charters them out for moving various other very large things from place to place, making a tidy profit on the side.  Not so with the Dreamlifters, which are used exclusively in the airliner-transport role.
Why is it that Airbus charters out spare Beluga capacity, but Boeing keeps their Dreamlifters all to themselves?

The 747LCF cannot haul any cargo except Boeing’s own cargo as its type certificate only allows it to carry Boeing’s own cargo.
Whereas A300 Beluga’s type certificate limitation section only refers to Airplane Flight Manual. It may allows to carry other cargo with some conditions met.
—————————
Page 28 of A20WE, type certificate of 747, states

XIV - 747-400 Large Cargo Freighter (LCF) Major Design Change (Approved June, 2, 2007 ) Transport Category
Allowable cargo
These airplanes are not approved for commercial freight hauling operations of material other than that approved per Exemptions 8769, 8769A and 8769B. Only cargo that supports Boeing corporate lines of business is allowed for carriage. All items intended for carriage must conform to the standards found in Document D926U013-44, “747-400 LCF Flammability Acceptance Criteria for Cargo Carriage,” or be accepted by the FAA once a safe method of transport has been established. A summary of all items allowed for carriage is identified in Document D451U742-01, “Allowable Cargo – 747-400 Large Cargo Freighter.” Document D451U742-01 is considered part of the Weight and Balance Manual/Airplane Flight Manual. In addition, a listing of the FAA-approved shipping mechanical equipment (SME) fixtures that are approved for installation on the 747-400 LCF aircraft are contained in the Weight and Balance Control and Loading Manual (Document D043U545-BHC1).

But this is really not a complete answer,  it's just "because the FAA says so".  Is there a good reason why they said so?

No idea as of now but I think it makes it easier for Boeing to certify the plane to carry its own cargo. FAA even restricted what can be carried as a cargo so Boeing cannot just one day say a power plant generator is to “supports Boeing corporate lines of business”.

@ymb1: In that case, why have the Dreamlifter's certification restricted so that it can't make more money on the side and help to improve Boeing's finances?

@Sean, it depends on how much extra revenue they think they could get compared to how much the additional work to get general certification would cost. Also the changes could make it less efficient for the primary purpose and then it would make even less sense.

TL;DR: Between the development of the Beluga and the Dreamlifter, the An-124 took over the commercial large cargo market. Therefore, Boeing didn't have a business case for charters.
As mentioned in vasin1987's answer, the A300-600ST Beluga is certified for commercial operations whereas the 747LCF is not. Airbus originally intended the aircraft to be available for charter, so they went through all the certification work, whereas Boeing did not.
The reason why has to do with the time periods in which both were built. The Beluga project began in the early 1990's. Consider the very large haul capability at the time: the US military-only C-5, the aging Guppy, and the An-124.
The An-124 would be well suited, except at that time, it had no civil certification and Ukraine and Russia were still getting over from the collapse of the Soviet Union. Prior to that, it would be politically difficult in many places to do business with Aeroflot, the Soviet Union's air carrier.
By the 2000's, Antonov and Russian operators realized there was a heavy lift market, and their aircraft was very well suited for it. Airbus was successful, and with increasing production rates so the Belugas were needed for internal use. The An-124 took over the charter market.
It was under this context that the 747LCF project started. Both the Beluga and the Dreamlifter have high cargo floors that require special equipment or crane for loading, a severe disadvantage against the An-124. So Boeing didn't have a business case to pursue charters.
Things have changed once again, with the political situation between Ukraine and Russia, the An-124 may not have support, so keep an eye out for what will happen.


text:
Why weren’t the Comet’s overhead ADF windows roundified along with its passenger windows?
Following the crashes of two Comet 1s in early 1954 due to metal fatigue, all future Comets (and the few surviving Comet 1s that were rebuilt rather than scrapped, all of them in military service) were redesigned to mitigate fatigue stresses; among other changes, the passenger windows were changed from round-cornered squares to circles.  However, the windows in the roof of the forward cabin for the aircraft’s ADF antennae, which are of almost identical construction to the passenger windows except for being filled with opaque fiberglass (in which the ADF antennae were embedded) rather than transparent panes, and which are considered to be one of the two possible locations (the other being one of the passenger windows) for the rivet hole that gave birth to the fatal crack in one of the crashed Comets (no wreckage was ever recovered from the second crash beyond that floating on the surface, as the depth of the water would have made salvage operations cost-prohibitive at the time), retained their original rounded-square shape.  Admittedly, the Comet’s subsequent service history seems to have vindicated this judgment (no Comet would ever again break apart in the air from fatigue damage, despite still having squarish ADF windows), but de Havilland didn’t know that at the time, and they thought it prudent to roundify the passenger windows, so why didn’t they do the same for the ADF windows?

It wasn't the square-ish windows (they still had round corners, just not as rounded as modern square windows).  They knew square windows were less than ideal stress wise and built the frame structure to take the expected loads.  They just screwed up the calcs and didn't quite make them heavy enough.
The problem was stress concentrations at the rivet holes in the areas of the corners were higher than calculated.  They could have just beefed up the structure with more rivets and doublers.  The switch to round was to alleviate the stress problems without the weight penalty of reinforcing the structure.
The holes in the roof were already sufficiently beefy, or perhaps they added a reinforcement.  You will see square holes in pressure hulls on various airplanes for component pass-through all the time, where a square hole is desirable for some reason.  If you make the frame heavy enough, it's not an issue.  It's just that a round hole is a bit lighter than a square one so most of the time a round hole is preferred.

Its worth noting that the Comets series of accidents triggered a massive investigation into the field of metal fatigue, resulting in significant additional research done into the matter - it wasnt simply a case of "they screwed up", it was more of a case of "the accidents exposed a deficit in knowledge" which was subsequently filled in to the benefit of the entire aviation industry (test results and research papers were shared with the aviation community).


text:
How to maintain your pitch when looking for other traffic in the pattern?
I am a student pilot and I fly in a desert region where turbulence often changes the pitch and airspeed of my aircraft.  I am having an issue maintaining pitch while scanning for other aircraft in the traffic pattern (I lose sight of the horizon while scanning).  I might scan for 2-3 seconds and by the time I bring my eyes back to the horizon my pitch has changed 10 degrees and I have lost 5 knots of airspeed.  My flight instructor then scolds me for not holding my airspeed.  Is there a way to scan for traffic while still maintaining reference to the horizon?

When you say that you "lose sight" of the horizon, do you mean that it's literally no longer in your field of view at all, or do you mean that you're no longer looking directly at it?

@Tanner Swett:  I guess I mean that I am not looking directly at it.  I suppose I just need to learn how to use my peripheral vision which is probably not very good since I sit at a computer all day.

I got my license about six months ago. My problem is that when I am not paying attention ( trying to change frequency or trying to get the GPS to do something etc), I always end up turning and going off course. This after 100 hours of flying. Holding altitude/pitch is for some reason not a problem. I think the stability depends upon the plane. Is there an option to fly a different plane?

When starting out as a pilot you are normally overwhelmed by all the tasks you need to do. Most of these tasks become second nature with time and experience. Here are some tips you could try.
Make sure the aircraft is trimmed correctly for the manoeuvre so that you do no need any force on the controls to keep the aircraft straight and level. Sometimes you can create your own turbulence because you did not trim correctly but then fight the controls.
Listen to the air noise. You could easily pick up from the change of air noise if the aircraft is loosing or gaining airspeed. A ten degrees pitch change will cause an airspeed change you will pick up by ear. Remember you are flying VFR so looking outside at the horizon to judge your pitch is very important. Flying the correct power setting and maintaining the correct pitch will help you a lot in flying because the aircraft will settle at a certain speed all by itself.
Maybe schedule your flying lessons when the air is more stable and turbulence is minimum. As you gain experience you will be able to handle the turbulence better.
Also try another instructor. Maybe another instructor might be able to understand your weakness and strengths better and handle the situation differently.
Ask many opinions from other pilots in the area. You will find that there are more than one technique sometimes. Just find the one that works for you.

Start by trimming the plane so you need minimal input to hold a current pitch.  Try to practice that a bit to really get it right.  Practice at different attitudes.. climbing, descending, and level flight.
Also, your cross check needs to be as fast as required to maintain control of the aircraft.  That means every 2-3 seconds is too slow.  Until you get the trim settled out, I would speed up the crosscheck.  While you are scanning outside, just come in to your instruments for a quick peek, then back outside.  Do that cross check cycle more often.


text:
Was there a TCAS alert during the near miss at Austin TX, where a Boeing 737 was mistakenly cleared for takeoff in front of a 767?
On February 4th 2023, there was a near miss at the airport in Austin TX, where a 767 performing an auto land in foggy conditions nearly collided with a 737 that was taking off on the same runway.  The Tower Controller mistakenly cleared the 737 for takeoff with only a 3 mile final for the 767 and resulted in a near miss.  The 767 initiated a go-around after noticing the error and barely avoided disaster.
My question is if the TCAS of the 767 would have issued an alert with the 737 on the ground?  Does TCAS only work for aircraft in the air or can it also issue alerts for runway incursions such as this one?

Please rephrase your question to ask about the general case, not a particular incident. The answer by BowlOfRed will remain valid. Questions speculating on accidents/incidents still under investigation are specifically off-topic on Av.SE.

Per the FAA booklet: Introduction to TCAS II, it does not alert against ground targets.

The ground level estimate is then subtracted from the pressure
altitude received from each Mode C equipped nearby aircraft to
determine the approximate altitude of each aircraft above the ground.
If this difference is less than 360 feet, TCAS considers the reporting aircraft to be on the ground. If TCAS determines the
intruder to be on the ground,
it inhibits the generation of advisories against this aircraft.

This has me wondering ... the altimeter has the local air pressure set, and will always have some error ... The radar altimeter less so, but I'm sure it still does. How is estimated elevation of ground calculated, and/or why not simply use the radar altimeter value in the first place? I wonder what the algorithm/calculation actually is.

After thinking a bit more, is TCAS using the radar altimeter, and that chart is actually just saying the error between the RA and the baro altimeter is called "estimated elevation of ground"? (I'm not a pilot)

RA isn't always available, so pressure altitude is normally used.   Local air pressure isn't used.    So it doesn't know how far another plane is above the ground, just approximate MSL (which is fine for collision detection).    It has to guess if it's on the ground based on the local height (which may be very different some distance away).


text:
A Question about Departure Procedures at KLRU
The Las Cruces International Airport has the following text in the Takeoff Minimums and ODP document:

LAS CRUCES, NM
LAS CRUCES INTL (LRU)
   TAKEOFF MINIMUMS AND (OBSTACLE)
  DEPARTURE PROCEDURES
  AMDT 2 16231 (FAA)
  TAKEOFF MINIMUMS: Rwys 4, 8, 12, 22, 26, 30, 2500-3
  for climb in visual conditions.
VCOA: All runways, obtain ATC approval for climb in visual
  conditions when requesting IFR clearance. Climb in visual
  conditions to cross Las Cruces Intl southwest bound at or
  above 6500 on CUS VOR/DME R-038 to ZAXOX INT/
  DMN 27 DME. Continue climb in ZAXOX holding pattern
  (hold W, right turns, 094° inbound) to cross ZAXOX at or
  above MEA or assigned altitude for route of flight

What I don't understand is if these procedures are optional or required.  While I understand that part 91 doesn't have to abide by Takeoff minimums and ODPs, would a commercial carrier be expected to do the VCOA?  In IFR training they said VCOAs can be requested but not offered by ATC.  Would a commercial carrier be expected to do the VCOA or could they do a Diverse Departure?  Also do the Takeoff minimums only apply to the VCOA?
Link to document Here

I think you are mistaken about whether Part 91 has to follow procedures other than takeoff minimums. Suppose a departure procedure requires a minimum climb of 275’ per nm. The reason that climb gradient is required is because if you don’t climb at that rate you will most likely hit something. I could be wrong, but Im pretty sure that if you accept a departure procedure, then you have agreed to follow it—regardless of whether you are Part 91 or not.

Also, diverse departure in not an option at this airport. When you see inverted triangle with a T symbol— Alternate Takeoff Minimums on the approach plate, it means that either there are non-standard takeoff minimums or that there is a published departure procedure. Airports with a diverse departure (not radar diverse departure) do not have published departure procedures and this airport does. Alliance Muni, Dodge City, Harper Muni, Neodesha Muni, Platsmouth Muni, Pratt, Smith Center, Cessna Field are examples of fields with diverse departure procedures—in Kansas with no obstacles for miles.

The only takeoff departure at Las Crucas, NM (KLRU) is a visual climb over airfield (VCOA).
Typically you would depart the airport and visually see and avoid the obstacles around the airport while you climb.  If you are in IMC conditions (at this airport) you need 2500' ceilings and 3SM visibility to circle and climb above the airfield.  In essence, the procedure is for you to avoid the obstacles while you are climbing in a confined space.
ATC wants to know about your intentions of flying VCOA so they can plan accordingly.  It is one thing to climb over the airfield to the MEA vs. reaching the MEA 30NM from the airport.
From AIM 5-2-7

A VCOA procedure is a departure option for an IFR aircraft, operating in VMC conditions equal to or greater than the specified visibility and ceiling, to visually conduct climbing turns over the airport to the published "climb-to" altitude from which to proceed with the instrument portion of the departure.  VCOA procedures are developed to avoid obstacles greater than 3 SM from the departure end of the runway as an alternative to complying with climb gradients greater than 200 FPNM.  Pilots are responsible to advise ATC as early as possible of the intent to fly the VOCA option prior to departure.


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Why do some Caravelles have a full outboard wing fence, and some only a partial outboard fence?
The Caravelle has two wing fences on each wing, so as to limit the spanwise airflow (and associated tip-stall problems) that would otherwise occur due to its rearward-swept wings.
On most Caravelles, such as this VI-R, this takes the form of a large inboard fence which wraps around the leading edge of the wing, and a smaller outboard fence which starts significantly behind the leading edge and rises only about half as far from the wing's surface as the inboard fence does:

(Image by Lars Söderström at Airliners.net, via Dura-Ace at Wikimedia Commons, cropped by Dura-Ace at Wikimedia Commons.)
On most 10Bs and all 12s, in contrast, the outboard fence is larger (although still not quite as large as the inboard fence) and wraps around the leading edge in the same manner as the inboard fence, as can be seen on this 10B:

(Image by Aldo Bidini at Airliners.net, via Russavia at Wikimedia Commons.)
However, some 10Bs, such as this one, have the older, smaller design of outboard fence:

(Image by Felix Goetting at Airliners.net, via Fæ at Wikimedia Commons, cropped by Fæ at Wikimedia Commons.)
Why the two different styles of outboard Caravelle wing fences?  I'm wondering if it might be related to the modified wing used on the 10B and 12, but, if so, then why do some 10Bs have the older style of outboard fence?

Every square inch of skin surface adds to induced drag, so nothing is going to be bigger than it absolutely needs to be. Whether through math or empirical testing (or some of both), it was determined that the outboard fence could be as small as it is. Therefore making it larger was detrimental to range, fuel economy, speed and cargo/pax capacity.

Then why do some 10Bs have the smaller outboard fence, while most 10Bs have the larger outboard fence?  If the 10B doesn't need the larger outboard fence, then all 10Bs should have the smaller one; if the 10B does need the larger outboard fence, then all 10Bs should have it.

"Every square inch of skin surface adds to induced drag" - I'm sure you meant to say friction drag, right?


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Why did the Concorde have a prohibition on droop-nose/windscreen-visor operation below 500 feet AGL?
Part of the Concorde's aircraft limitations, from this answer:

The last line of the given excerpt, and the one that this section concerns, reads:

Nose and/or visor operation must not be made below 500 ft above the terrain.

Why this particular limitation?

Perhaps to give pilots some room to get used to the different sight picture, including any optical distortions?

It would also violate “stabilized approach” criteria.  And for what reason?  Below 500’ you ought to be in takeoff or landing configuration and not monkeying with major changes to the airplane.

@MichaelHall: That sounds like answer material!

The moving visor provided a large horizontal line in the pilot's view that moved up or down. This attracted the pilot's attention and they tended to pitch the aircraft together with the movement of the visor - which was usually not desirable below 500ft.

Seems reasonable. Do you have a reference?

ISTR reading this as a caution in the handling part of the FCOM years ago, and as a handling pilot I noted it as something to watch out for. It wasn't actually a problem once I knew to look out for the effect.

I can’t speak with any authority on Concorde specific requirements, but it seems that changing the nose droop angle would be a fairly major configuration change.  Below roughly 500’ AGL aircraft are generally considered to be either in the take-off or landing phase of flight, and manufacturers and airline operators prohibit configuration changes at low altitude.
Take-off phase – Take-off power and best climb speed are used to get safely away from the ground.  With the exception of retracting the landing gear, nothing else but basic pitch control is touched.  (roll control and rudder as needed to remain wings level, but no turns initiated)  Above some predetermined acceleration height, (may vary by airline SOP, but 500 AGL is a good approximation) the aircraft is gently nosed over to accelerate to flap retraction speed.  Around that time when the flaps are up the power may also be reduced somewhat to climb power for engine life and/or noise abatement procedures, and the aircraft may turn on course as it transitions from takeoff to climb phase.
Landing Phase – Below 1000’ AGL the aircraft should be ready for landing as the crew prepares to transition from approach to landing phase.   For compliance with Stabilized Approach criteria, this requires that the aircraft be configured for landing, (gear, flaps, etc.) with the “etc.” in this case presumably covering the nose droop.  Below 500’ especially the crew needs to be focused on instrument approach minimums and transitioning their scan to the runway environment for landing.  I don’t know what sort of aerodynamic changes the nose causes, but it just doesn't make sense from a best practice standpoint to make any sort of change down low on a fast moving jet that is probably 20 seconds or less from touching down.

Though I think your intent is correct, the actual statement is patently false: "manufacturers and airline operators prohibit configuration changes at low altitude." Gear and flap retraction both occur below 500 ft AGL routinely and procedurally.

@MarkJonesJr., FWIW, both operators I have been involved with set an accel height of 400’ AGL. I intentionally avoided declaring some universal limit by using the generic terms “roughly” and “low”, and furthermore added “may vary by airline SOP, but 500 AGL is a good approximation” The question itself is evidence of at least one Mfg setting a limit of 500’. (I also excepted ldg gear retraction.) If you have credible knowledge or evidence that airlines routinely retract flaps significantly lower than 400-500’ AGL then please offer it. Otherwise I stand by my loose, vague, generic claim.


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What is this thing apparently attached to the bottom of this Caravelle's engine, and why is it there?
This Caravelle 10B appears to have something mounted on, or stuck to, the lower surface of its No. 2 engine nacelle.

(Image originally by clipperarctic at Flickr, via Russavia at Wikimedia Commons; cropped and annotated by me.)
Photos of other Caravelles do not show a something of this sort under their engines.
What is this thing, and why does this particular Caravelle (and not others) have it?


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What is "Block burn" and how is it calculated?
I have heard a couple of times the term "block burn" in the aviation industry but I am not sure to what it exactly refers. My second question is how is it calculated? I have also heard it depends on seasonal data

Your questions suggest that you know more than you are telling us.

I actually don't. I am reversing an old legacy system and trying to figure things out.

I have no idea and no connection with the aviation industry so I looked it up. I found

Block Fuel / Ramp Fuel / Total Fuel On Board
Block fuel is the total fuel required for the flight and is the sum of the Taxi fuel, the Trip fuel, the Contingency fuel, the Alternate fuel, the Final Reserve fuel, the Additional fuel and any Extra fuel carried. Source: Skybrary.aero.

That in turn led me to look up 'aviation block' and I found

Perhaps you’ve noticed that flights flown on different airlines between the same airports take different amounts of time. You might reasonably ask: why would different flights, departing from and arriving to the same airport take different amounts of time? The total amount of time a flight takes — from pushing back from the departure gate (“off-blocks”), to arriving at the destination gate (“on-blocks”) — is called “block time”, and airline block times vary for the same routes. Source: FlightStats.

I guess that block burn is the amount of fuel burnt between the departure gate and the destination gate.

My second question is how is it calculated?

Start fuel - end fuel, I guess. This can then be tabulated and used for future flight block burn calculations.

I have also heard it depends on seasonal data.

Many operational factors will vary by season so this seems reasonable.


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Are the terms "Aircraft Version" and "Aircraft Variant" synonyms?
Related to the answer of the following question:
How are evolution and variants of aircraft considered by certification authorities?
Are the terms "Aircraft Version" and "Aircraft Variant" synonyms? The answer uses the term "Aircraft Variant" but I have also come across "Aircraft Version" elsewhere.

Possible duplicate of How are evolution and variants of aircraft considered by certification authorities?


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Flight Data Monitoring formats
I would be interested in learning more about Flight Data Monitoring  in order to build data analysis tools.
The most basic question I have, is whether Flight data is recorded using a standard format. If yes, where could I find additional information about this, including sample data

What flight data, specifically?

@ymb1 Yes indeed those questions have answers to mine. My question is a duplicate

@GdD the obvious data such as latitude, longitude, altitude. This can be easily obtained from websites. But also the less obvious: engine thrust, fuel burn.


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What does it mean when ATC says climb maintain 7000, block 8000?
I understand the climb and maintain, but what does block mean?

It means you've been allocated a block altitude - you can fly whatever altitude you want between 7000 ft and 8000 ft.
Typically this would be something you'd request, e.g. to practice unusual attitude recovery or to avoid having to hold a hard altitude in mountain wave.  It's unusual for ATC to volunteer a block altitude without the pilot asking for it, but maybe if previous aircraft along the same route reported difficulty maintaining altitude then ATC might offer it to you unprompted.

Block altitude is also often given to long-haul flights in quiet airspace. As fuel is burned the optimal cruise altitude increases. With a block altitude clearance the pilots can follow this optimal altitude increase instantly, per hundred feet if they desired, instead of waiting for it to reach the next standard cruising altitude.

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How to correct a roll due to turbulence?
I fly a Piper Cherokee 180 (PA-28-180) in an area that has frequent turbulence. When turbulence causes the aircraft to roll to one side I usually try to correct by using aileron and rudder in the opposite direction of the roll.
However my flight instructor says that I should use rudder only to correct for the roll. I can get the wings level by using only rudder but it seems to me that using aileron and rudder would be the most effective method. Can someone please explain to me why I should use only rudder in this instance?

I'm not sure I would agree with the advise of your instructor, but this is perhaps what he wants you to learn.
The Piper Cherokee has a small amount of dihedral built into it's wings. This dihedral angle is used to "self right" the aircraft in the event of a roll.
The way it works is when an airplane starts to roll it loses altitude parallel to the slip direction:

So with a dihedral angle the wing facing the slip direction now produces more lift:

With enough time dihedral wings will right themselves, or as your instructor is telling you, you can make this faster with the rudder by turning the lower wing into the relative wind speed making it produce even more lift.
Why your instructor is preventing you from using any ailerons I'm not sure, but perhaps he has reasons you should ask him about.
This might not be the best example, but I have something personal that probably relates to what your instructor's getting at.
I ride horses quite a bit, and we have something called "no stirrup Thursday".
It's as the name sounds, when you ride on Thursday the stirrups stay in the barn.
Stirrups help you balance your weight so by spending a day without them we force ourselves to learn to balance better and ultimately stay on the horse given a situation when our feet slip out of the stirrup.
It's not unheard of that control sticks break and all your left with is the rudder pedals.
It's also not uncommon for new pilots to use the ailerons too much to correct roll and this causes the plane to roll the other direction, which they then switch the ailerons back again to try and correct it.
But I'm really just speculating at this point, you should ask your instructor directly why he is preventing you from using the ailerons.

Your instructor needs some... instruction.  Inducing roll using rudder alone is something you do when you are right on the edge of a stall because a downgoing aileron can potentially induce a stall when right on the edge.   In a normal climb, using rudder alone is totally nuts.
Apply only the rudder required to keep the ball centered with the application of whatever aileron is necessary.   If you needed all the roll power you can possibly get, you would apply full aileron and full rudder to use the resulting skidding to increase the roll rate.

I'd urge you to exercise caution using this technique. After all, this is how American Airlines 587 got down.
The pilot used rudder aggressively in an attempt to get the plane out of a jet wash - so aggressively that his rudder input caused structural failure and the entire vertical stabilizer snapped. In post-crash interviews with other pilots who have flown with the accident pilot, others stated he like to use very large rudder inputs even in minor turbulence. When questioned about this technique, he said he was taught to use the rudder this way. Further investigations revealed that many pilots in the airline have a wrong concept of flying an airplane, namely using the rudder way too aggressively to correct the airplane's attitude.
Using the rudder is a very effective way to correct an upset situation. Say I find myself in a left bank 135 degrees (so I'm upside down) and nose down attitude. Full right aileron and full right rudder would be my input. My rudder input has two purpose. First, the roll-yaw coupling (on most planes) means my right rudder with cause induced right roll. Second, once the plane is at the vertical (90 degrees roll), the rudder pushes the nose up instantly. As I transition to upward flight, somewhere between 60 degrees to 45 degrees of bank perhaps, I'd slowly let go of rudder input and at the same time gradually pull the stick/yoke aft, careful not to stall or cause abrupt input, depending on airspeed.
But that's more of an extreme situation.
Another use case, told to me by a Boeing 737 training captain: in case of complete hydraulic failure, a slight pedal input will bank the plane in the desired direction. Again, this is an emergency situation, not normal flying.
Like others here, I do not agree with your instructor, or at least not in your presentation (you may have misunderstood him, which led to the rest of us misunderstanding him as well). For small attitude deviations, use the most direct method to correct. Use rudder to keep the balls centered. For larger deviations, aileron + rudder would be the most effective method. Again, we cannot judge how big those deviations are here. All I can say is - if you're dancing on the rudder pedals, it is definitely a wrong technique.

I somehow suspect it'd be hard to give the kind of rudder inputs seen in AA587 in a PA-28, unless of course said PA-28 has had the manufacturer's optional hydraulic rudder augmentation system installed.

Perhaps this is of some use. AOPA put out a video recently about using rudder to correct for some turbulence. I can't re-watch it just now, but as I recall it doesn't recommend always using rudder instead of aileron. Rather, it talks about recognizing when bank is induced by crosswind gusts and using the rudder appropriately.

The stuff in this video is basically what my instructor is trying to teach me.  Thanks for the link.

Not necessarily the best technique, but, in practice, say on a long cross country flight, use of rudder-only allows for the use of your hands to manipulate charts, plotters, portable electronics, etc. I have found myself doing this many times over the years. Just a thought.

This isn't answering the question @Walker, using rudder for small roll inputs is fine, but not for large inputs.

Turbulence, being quantifiable, may need to be stipulated. In the case of my own experience, the inputs don't need to be large or erratic. A little pressure and time do the trick. On the other hand, when crossing the Cajone Pass during a Santa Ana, lots of coordinated Aileron and rudder.


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Why do some turbofan-engined Caravelles, but not all, have an anti-shock body at the root of the horizontal stabilizers?
Many turbofan-engined Caravelles have a prominent anti-shock body where the horizontal stabilizers attach to the vertical tail, about a quarter of the way up the latter.  (Turbojet-engined Caravelles don't have it.)
For instance:

(Image by Aldo Bidini at Airliners.net, via Russavia at Wikimedia Commons.)
This Caravelle 10B, however, does not:

(Image by Rob Schleiffert at Flickr, via Helmy oved at Wikimedia Commons.)
Why do some turbofan-engined Caravelles have an anti-shock body in this location, while some other instances of the very same Caravelle variants lack one?

It looks like an application of area rule to compensate for the fan's lager nacelles, which were likely increasing the build up of the transonic shock wave behind the engines.

@JohnK: Then why didn't all turbofan-engined Caravelles have this anti-shock body?

Not sure, but the non-fan engine in the lower pic is quite a bit forward from the one in the top pic.  Maybe other turbofans also have the forward engine placement?

@JohnK: Both of the pictures in the question are of turbofan-engined Caravelle 10Bs.  The difference in apparent engine position is an artifact of perspective resulting from the differing angles at which the two aircraft were photographed.


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Why is the nose landing gear of a Rutan Vari Eze up during parking?
I recently saw a Rutan Vari Eze parked at the airport and I was wondering why the nose landing was up during parking. How does it work for a pilot to get in? Can the pilot put down the landing gear while sitting in the cockpit or has the pilot to put it down while standing outside? And what's the idea behind such a construction, why isn't there just a normal landing gear?

Rutan Vari Eze during parking, with the nose gear up

Rutan Vari Eze before takeoff, with the nose gear down

For getting in, the nose has to be physically raised before the pilot can board the aircraft:

When the aircraft is parked, the NLG is retracted and the aircraft rests on the bumper at the front of the aircraft, in what is described as the 'kneeled' position.
Extension of the NLG requires the front of the aircraft to be physically raised, after which the NLG extension system is operated from the cockpit.
To begin the NLG extension, a handle in the cockpit is turned in he extend direction. This handle is connected to a shaft that turns a worm gear and crown wheel, and the rotation of the crown wheel drives the actuating rms of the NLG in the down direction.  When the NLG is extended, an extra 1.5 turns of the handle causes the crown wheel to drive the actuating arms over-centre, which locks the gear in the fully down position.

After this, the pilot boards the aircraft. On some aircraft, linear actuators seems to have been fitted for this purpose:

In recent years the application of general purpose, 12 volt, linear actuators came into use for electrical actuation of the nose gear with the airplane loaded.
With the linear actuator the airplane can be parked nose down for stability, boarded (in the nose down position) and raised by the push of a button.

As noted above, this design has been adopted for stability- As the engine is on the rear, if the pilot is not in the aircraft, it can tip backwards, damaging the propeller. This also acts as a parking brake.

FWIW, actually getting in to a VariEze is much easier than describing how to get into one!

Very interesting to hear. Such a construction can only be from Rutan.

Ah, the KSP method of staying put when parked.

From the Wikipedia article:

In place of a parking brake, the plane's nosewheel retracts until the nose rests on the ground. Resting the nose on the ground also moves the plane's center of gravity forward relative to the main landing gear, which prevents the plane from tipping onto its rear when there is nobody in the pilot's seat to weigh the nose down.

It's not at all unsurprising that this is a Rutan aircraft; certainly it could have been designed with a different layout and more conventional landing gear, but Rutan seems to design things differently simply because he can. It might be impractical, but it's a lot more fun!

I'm not sure it really is impractical though. Along with eliminating the weight/complexity of the parking brake, the nose-down attitude means the airfoils are almost certainly lifting downward, so given a strong wind from a generally front-ward direction, they will be pushing the plane down onto the ground (where most planes would be producing lift). This should help keep them stably parked in event of a storm (or similar).

AFAIK, one of the stated goals of the design was self-recovering stall, which is naturally achieved with the canard design. Which, in turn, favours pusher prop, which makes a tail boom difficult to design, which then leads to VariEze layout. Which is naturally tail-heavy without payload. So... I think it's a very efficient and reasonable compromise for this class of aircraft.

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Where does the Garmin G1000 Nav ID come from?
If you tune in a NAV frequency into your G1000 the ID of the Nav Aid will be shown next to the frequency after some time. In this example SEA:

Source: http://krepelka.com
How does this work? Because we know that there is the possibility that two VORs could have the same frequency, so the frequency is not uniquely bound to an identifier.
I have two assumptions:

The Garmin is listening to the morse code, transfers it into the letters and shows it in the display.
The Garmin is checking the Nav database and searches for the frequency and takes the identifier of the closest, based on the GPS position.

Which one is right, or is there even another way Garmin does it?

I would suspect a combination of the two.  ID the morse code, check the GPS to see that it makes sense.

Related: Is VOR identification automated in modern avionics?

Garmin doesn't explicitly state the method in the documentation I can find, but I believe the answer is #1. It decodes the Morse code and displays that value. I say that for two reasons:
First; Garmin, like most successful aviation companies, makes it a habit to reuse technology where it can. Volumes are low and certification costs are high so using the same NAV receiver in more than one product saves costs and increases profit. From their web site, the GNC 225 decodes the ident.

Automatically displays tuned frequency's navaid or airport identifier
Automatically decodes Morse signals so you don't have to

Second; the fact that it takes several seconds for the ID to display indicates it's being decoded as it has to be received before it's displayed. If it were pulled from the database, it would be available almost instantly.

Sometimes the ID comes up really fast so I thought that would be impossible... But maybe you will get the ID a lot earlier than a bearing on the HSI.

This is the only I do I could find. It states that it will identify regardless of the Morse code.

Since the only way to verify that you are receiving the correct signal from a working VOR is to listen to the Morse Code, it is very likely that the G1000 is decoding the Morse Code. If it were only using the database, the pilot is likely to miss a test code or the fact the code is missing all together in the case of a facility under maintenance.


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What's going on with sudden acceleration/deceleration in mid-air?
I was recently on a flight between LGB and PHX. I've been flying since I was 5, am now 31. After takeoff, as the plane approached cruising altitude, the plane slowed down. A lot. Then accelerated again, followed by another slowing down. This happened at least 4-5 times during the short flight, and before landing we made a complete circle around the airport, I'm assuming to comply with which runway to land on. My question is: why, or what cause, does a plane slow down in mid flight where you move forward in your seat, like hitting the brakes in your car too hard multiple times. I understand training and all that, I want to know the cause. To put it in perspective, I assumed the engines stopped. And to increase the nausea, we were delayed by a mechanical issue for an hour.

Are you sure that the plane slowed down? Your inner ear and your body can only feel acceleration, they cannot tell where that acceleration comes from, it will always be the sum of all accelerating forces acting on your body. For example: if the plane accelerates with 1g, you will be pressed into the back of the seat with your entire body weight. If the plane stands on its tail without moving, you will actually be accelerated downwards by gravity with 1g, i.e. you will be pressed into the back of the seat with your entire body weight. The sensation will be exactly identical, you cannot …

… tell the difference without having a reference to the attitude of the plane with respect to the gravitational field. Likewise, the sensation of decelerating is the same as the sensation of pitching down: you fall forward in your seat. Unless you can see the horizon, you will not know the difference. Note that even trained pilots typically lose orientation after less than 15 seconds after losing visibility, unless they are trained to not trust their body and ignore every cue and just look at the instruments. They can be upside down plummetting to the ground and swearing they are just in a …

turn trying to get out of the cloud.

An aircraft can't decelerate that rapidly in flight. Spoilers aren't very effective as the disk brakes on the wheels, and reverse thrust, which are both used on the ground. Someone should be able to quantify the typical max rate of deceleration in cruise, but I can't see it being very high. So, it was probably more a sensation of decelerating, which maybe caused by pointing the nose down, than a real deceleration. If you have ever watched an aircraft simulator, it tips forward and backwards, but inside, you think you are accelerating and decelerating.

"I assumed the engines stopped" If the (all) engines ever do stop in mid-flight on an airliner you're on, then trust me, you'll know.

Most airliners broadcast their position and speed every second for purpose of air traffic control and collision avoidance and in addition to the ATC systems, these data are collected by a couple of sites like https://flightradar24.com and https://flightaware.com. If we knew the exact date and flight number, we could try to look what actually happened (FR24 shows 7 days history publicly and more only to subscribers, so in 1 week the chance to check is much better).

@JörgWMittag Please move your comments to an answer. They do consists of a reasonable explanation and don't need to in comments.

Without knowing the specifics of the flight, there could be a lot of reasons for this.
One guess for the sensation of accelerating and decelerating We’re intermittent steps at fixes on the departure procedure the pilot flew out of KLGB at certain altitudes and airspeed either as part of the DP or as assigned by ATC in order to facilitate departure from SoCal airspace to enroute.  That and a little sloppy airmanship on the part of the flight crew.
As for the “circling” at KPHX,  most likely that was the pilot flying a STAR with ATC final vectoring to a visual approach or SIAP for runways 25L/25R/26 at Sky Harbor Intl.


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Why do semitailless swept-winged aircraft, but not delta-winged aircraft, suffer from (primarily) pitch oscillations at high mach?
Semitailless1 swept-wing aircraft without active stability enhancement2 generally3 have extremely poor handling characteristics, most notably a tendency towards violent pitch oscillations at high subsonic mach numbers, and yaw and roll oscillations at mach numbers slightly beyond this.  As a result, while the swept-wing semitailless layout was briefly quite popular for transonic and supersonic aircraft in the late 1940s and early 1950s (witness, among others, the DH 108, X-4, and F7U), it was quickly abandoned, only making a comeback much (much) later, with the advent of computerised active-stability-enhancement systems.
In the meantime, supersonic aircraft near-universally switched over to delta-winged layouts, which worked just as well for supersonic flight and had none of the nasty quirks of semitailless-swept-winged layouts.  This despite the two layouts being extremely similar; indeed, a semitailless swept-wing aircraft can be seen as a delta-winged aircraft with part of the inboard trailing edge cropped out:

Why do two such similar layouts have such different handling characteristics?

1: Aircraft that do not have a separate horizontal tail, but do have a vertical tail.
2: A system where a computer constantly monitors what the aircraft is doing and continually makes tiny flight-control inputs to keep it doing what it's supposed to.
3: Although not always.

Lovely diagram, especially the pitch excursions.

The function of a "tail" in this case is pitch stability.  Therefore, all stable aircraft must have "tails".  Aerodynamically, the rear portion of the delta is its tail.  Removing it should have predictable consequences, even in the subsonic realm.
Transonically, with shock waves dancing on the wings and a moving center of pressure, pitch stability is critical.  This is also true in slow flight, where a shifting center of pressure can overwhelm weaker pitch stability.
Subsonically, the swept tailless design can be helped by "washing out" (lowering the AOA of) the wing tips or by adding slats, which helps control movement of the center of pressure at higher angles of attack.  As Dunne ingeniously realized over a century ago, this design made for a stable aircraft.  Indeed, a swept wing aircraft with insufficient tail area could be helped with stronger slats!  (If the wing tips can handle the extra load).
Transonic and supersonic flight is another issue.  The notion of "taillessness" was a blind alley in aviation design, a mistake not to be repeated.

That still leaves the rear portions of the outboard wings, though, which should be able to provide pitch stability on their own.

They do, but if the (swept) tips stall first, stability is lost.  Notice on (even modern) supersonic aircraft, the vertical (usually 2) and horizontal stabilizers are oversized.

The Me 163 actually had fixed wing tip slots and a relatively unswept low aspect wing.  It is a excellent glider.

And to make it so that the wing roots stall before the tips, aircraft with rearward-swept wings need significant washout (decrease in angle of incidence going from the root to the tip), which makes the wingtips fly at a lower attack angle than the wing roots... which (as the wingtips are located considerably aft of the wing roots, such that the washout ends up also expressing itself as a considerable degree of decalage), conveniently enough, also takes care of pitch stability!

@Sean but very draggy.  Retractable slats are much better.

...riiiiight, which just so happens to explain why washout is ubiquitous on swept-wing aircraft, whereas slats aren't.

@Sean  Airliners like them, but washout is simpler.  A straight wing and a properly sized horizontal stabilizer is good too.

The pitch oscillations come from the transsonic air coming off the main wing and interacting with the elevators/Stabilators.  If you look at the variants of the X-1 you will see that the one that broke the sound barrier has its elevators further above the main wings than the previous models

With a semitailless aircraft, the elevators are located on the main wings.  A semitailless aircraft, by definition, has no separate horizontal tail.


text:
Why is crushable-block EMAS the only overrunning-aircraft-stopping system in wide civilian use?
Because runway overruns often end badly, and many runway ends (especially older ones) don’t have enough clear space available beyond the runway end for a full-size runway safety area (RSA), EMAS has come into wide use (at least in the U.S.) for quickly stopping overrunning aircraft within a smaller-than-normal RSA.  An EMAS system consists of a bed of crushable pavement blocks (usually cellular concrete or foamed silica) which collapse when an aircraft runs over them, causing the aircraft’s landing gear to sink into the EMAS bed and drag through it, slowing the aircraft quickly to a stop.
However, EMAS is far from the only conceivable system for slowing and stopping overrunning aircraft:

One option would be a simple bed of sand or gravel (like the runaway truck ramps ubiquitous on steeply-inclined highways), which would slow an aircraft down through exerting drag on its landing gear; although not as effective as a full-blown EMAS, it would be capable of handling small aircraft that wouldn’t be heavy enough to crush the paving material of an EMAS, and would also be far less expensive, making it ideal for smaller general-aviation airports.1
In a similar vein to the sand/gravel arrestor bed, a thick bed of tall, stiff bristles would also slow aircraft fairly quickly through landing-gear drag (like how it takes a lot more effort to walk through waist-deep grass than on bare dirt).
Another possibility would be a large retractable net, similar to the nets aircraft carriers carry to stop aircraft if need be.  Although aircraft-carrier nets are, admittedly, usually used for aircraft considerably smaller than your average airliner, the aircraft more than make up for this by landing at very high speeds compared to an airliner and by travelling a much shorter distance (and, thus, having much less time in which to slow the aircraft by braking) between touching down and hitting the net than an airliner at a land-based runway would, and the aircraft do have the ability to handle the considerably-larger aircraft that sometimes land on aircraft carriers; additionally, nets were formerly used at emergency landing sites for the space shuttle orbiters, which were about the size of a DC-9, but much heavier and having landing speeds over twice as fast, strongly suggesting that similar nets would be capable of handling even large airliners.

So why is the crushable-block EMAS the only system widely used for stopping overrunning aircraft?

1: One airport does have sand-filled arrestor beds at two of its four runway ends; however, this airport serves aircraft large enough that it should have a full EMAS instead, the sand beds being woefully inadequate for stopping aircraft of these sizes, as was spectacularly demonstrated in 2010.  Sand/gravel beds are far better suited to stopping smaller general-aviation aircraft that aren’t heavy enough for an EMAS to be effective.

Technically St. Barts has a "sand arrestor" system...

BTW you can see that an aircraft running into sand is not a gentle thing, the nose gear collapses and the fuselage digs in. Gravel would be the same thing. EMAS is nice in that it doesn't severely damage the aircraft or the engines. EMAS needs to be designed for the average aircraft/biggest threat factor because as you know, there's no "one thing for all aircraft" that works equally well.

A Comair CRJ once ran into EMAS and the ldg gear supplier  (Menasco or Dowty, forget which) made them remove the gears to be sent in for inspection, but they were undamaged, just EMAS-blasted.  It took many many hours of polishing the EMAS-blasted inboard leading edges to restore the shiny surface finish.


text:
When to switch from ground to tower frequencies at controlled airports in the US?
I have heard that you can switch to the tower frequency once you are at the runway hold line and are ready for takeoff without getting permission from ground control to switch frequencies.  Is this always true or does the procedure vary for different airports?

As a general rule, don't leave a frequency unless you ask first or are told to do so.  There are very few exceptions to this rule of thumb.

Were you given instructions like "Taxi to two-four via golf-delta, contact tower on 122.7"? Usually following that type of instruction I stay on ground until reaching the hold point then switch over to tower and announce position and intentions.

@Ron Beyer:  I haven't taken off from a towered airport yet which is why I am asking.  Is that how ground usually gives instructions, the route then the tower frequency?

@DLH It depends on the airport, the ones I fly out of are not all that complicated taxi-wise, but in my experience yes, it is the taxi instructions followed by who to contact next. The important thing is to not change frequencies while under the control of ground. And if in doubt, ask (for everything, including if you don't remember if you can cross that taxiway/runway/hold line). Sometimes they won't tell me to contact tower if they are having me hold short somewhere else, like the ILS hold line.

Yes - and make sure you have an airport diagram pulled out, the routing can be tricky.  Don't cross any runways unless you have been told you are clear to cross them.

While I acknowledge the answer by GdD to not change frequencies until instructed, that is at odds with my experience.
When I call Ground, then request and receive taxi-instructions, I stay with Ground to the runway hold short line.   I've never had Ground give me an explicit instruction to switch to Tower.
When I start my run-up checks, I switch to Tower (unprompted) to start hearing what is happening in the airspace.  When my run-up is complete, I call Tower with a "ready for takeoff".
I've never had Ground, Tower, or any Instructor tell me differently.  I've never observed another pilot wait for an explicit frequency change instruction from Ground, and I believe that is the way I was taught.

Note: this only applies when you've taxied to the hold-short with Ground.  If Ground tells you to switch earlier, do it.  If you want to switch earlier, request it.

this is also my experience.

This is how we do it at my home airport also.

Centennial airport near Denver (KAPA) is an exception. After run-up is complete, you contact Ground and they will let you know when to switch to the Tower. I learned to fly there and didn't know that this was the exception until getting corrected at a few other towered airports. If you look in the A/FD for Denver Centennial there is a note telling you this under communication notes at the end of the entry.

Do you really say Ready for take-off and not departure in the US?

@VladimirF: While US phrasing does technically call for "ready for departure", at many small, low traffic airports, radio communication gets less formal, and admittedly, many people do say "ready for takeoff" even though they shouldn't.  I've also heard "Ready to go", and a variety of other phrasing.

I have found this AIM 4-3-14a which I believe answers my question:

AIM-4-3-14a:
  Pilots of departing aircraft should communicate
  with the control tower on the appropriate ground
  control/clearance delivery frequency prior to starting
  engines to receive engine start time, taxi and/or
  clearance information. Unless otherwise advised by
  the tower, remain on that frequency during taxiing
  and runup, then change to local control frequency
  when ready to request takeoff clearance

This seems to suggest that it is OK to switch to tower once you have completed the runup and are ready to takeoff at least in the US.  Also interesting here is that it says that you should contact clearance/ground prior to starting your engine.  I have never heard of that before.

"This seems to suggest that it is OK to switch to tower once you have completed the runup and are ready to takeoff at least in the US. " I don't think that is what it is suggesting, especially if you are flying VFR. It is saying to contact tower on the appropriate ground control frequency. From then on "tower" is referring to the ground control frequency, not the frequency you get your take-off clearance from (local control frequency). The AIM writes this very cryptically.

@RonBeyer - I'm not seeing what's different in your comment vs. DLH's answer. In both cases, you're staying on ground control frequency until after runup, then switching to local control frequency when ready to request takeoff clearance. I think the point DLH is making here is that there's no need to make a specific request to change frequencies, it's part of the procedure post-runup.

@T.J.Crowder The difference is that you are assuming that the run-up takes place at the end of the active runway or on the taxiway just before you need to switch. My experience at towered (Class-C) airports is that they really do not want you to do that. Either they have designated run-up areas or they assume you will be ready to go when you call ground for your taxi instructions. Running up at the end of the active with traffic behind you will not make you any friends at a busy airport.

@RonBeyer - If the runup is in a designated runup area, clearly you're going to taxi from there to the runway, so you're going to stay on the ground frequency per the above. I don't think DLH was suggesting otherwise. Hope not, anyway.

@T.J. Crowder:  I took the regulation to say that when you are ready to take-off you can switch to tower unprompted which means having performed your run-up and taxied to the hold short line.

@DLH - Yeah, that's what I thought you meant.

If you are under control of ground you only switch to another frequency when directed, or are granted permission. They'll tell you "Contact tower on xxx.yy", for example. You might ask to change, say you only have one radio and you want the latest ATIS, in which case you request to change, and wait until they give you positive indication that is okay. You may need to shut down your avionics to start up your engine, especially common in light singles, in which case you ask permission for that as well.
If ground goes off of the air or you have trouble contacting them you can change to a different frequency for a radio check, or if there's some sort of emergency requiring changing frequencies to resolve then do so, it's hard to think of a realistic case for that; if you have an emergency on the ground then ground is best placed to help you.

authors: Vladimir F Героям слава


text:
Are there any data on the safety rate of gliders vs single-engine GA aircraft?
Can anyone point me to statistics on the safety record of gliders vs. single engine general aviation aircraft?

NTSB Accident Database 2326 entries for "Glider" aircraft type, submitting a request for just "Airplane", 1 engine, and "General Aviation" chokes the result. I'm not sure which statistics you are looking for (total accidents, fatalities, incidents, etc).

@Ron Beyer:  Accidents per 1,000 flights or accidents per number of pilots would probably be a good metric.

I think you cannot reasonably compare that because flying gliders has completely different hazards than flying powered planes.

@TimothyTruckle Yes, but which is safer?  The hazards are different, but surely one is overall more or less safe.  I would think that a standard metric of accidents / x hours of flight time or accidents / x flights would be the appropriate way to compare them.

Flying both, I actually feel quite a lot safer in a glider.  This is mainly because of the ability, once you have acquired a bit of skill, to place the glider exactly where you want to thanks to the flat glide + dive brakes that give a huge range of choices.  In a medium performance or better glider, if the tow rope breaks at 300 feet, you can pretty much complete a full circuit.  On rope break training at low altitude where you turn straight back, most students are shocked to find the problem isn't making it back, it's not overrunning the landing area with the tailwind.

@John K:  That is my impression as well.  That's why I am looking for statistics to confirm that.

Fascinating question.  Do you think that the injury/fatality rate would be salient?  Gliders experience off-field landings more often (I think), but those landings are probably safer due to the glider's excellent control of glide path (as @JohnK mentions), and its low approach speed.  So perhaps the gliders get broken more often, but the pilots get broken less often.

I'll go out on a limb and speculate that the majority of glider fatals are stall/spin at low altitude, followed by midairs.  The midair risk, especially in competition where thermals can get pretty crowded, is the main reason single seaters generally have parachutes.  I personally witnessed a fatal midair at  a club I used to belong to when two pilots thermaling close to the field ran into each other at about 1400 ft.  One survived because his glider, its tail boom chopped off, disintegrated immediately and he had nothing to do but pull his ripcord.  Other guy stayed with it and crashed.

What about factoring in the number of seat-miles? Or the vastly improved utility of powered aircraft? Or comparing the number of seat-miles/hour of aircraft and gliders over a route of 1,000 miles/kilometers

Still no firm answer on this yet....

I had three days to burn so I took a look.)
Comparative data was very difficult to find beyond accident counts, so determining relative safety is problematic. No one that I could find tracks or estimates the number of flights/hours for gliders, even the Soaring Society of America, so this is all interesting but essentially meaningless. Even if such data existed, the difference in use models would cause problems making a fair comparison. So now that I've told you this was a waste of my time to compile, I will make you waste your time to read.
If you could extrapolate single mode pilot certificate counts to a common usage basis, flying a glider is 2.5x safer than flying an airplane, but of course you can't.
NTSB accident count for 2017 shows 56x more airplane accidents and 90x more fatal airplane accidents than glider accidents.

271 fatal and 972 non-fatal GA airplane accidents, total 1243
3 fatal and 19 non-fatal GA glider accidents, total 22

US Civil Airmen Statistics shows 18x more airplane only pilots than glider only pilots, with 40-80% of both numbers muddied by multiple certificate pilots.

14k registered glider only pilots
24k registered glider pilots with multiple certificates
260k registered airplane only pilots, excluding ATPs
190k registered airplane pilots with multiple certificates, excluding ATPs

AOPA had a report for 2009 for all general aviation where the accident rate per 100k hrs is 7.2, and a fatal rate for the same of 1.33.

Thanks for putting in so much effort to answer the question!

@DLH It was an interesting question and I was curious. Not every question gets a clean answer. Sorry.

Gets my +1 for "So now that I've told you this was a waste of my time to compile, I will make you waste your time to read." if nothing else! :)

I found a blog post that answers the question by using commercial aviation as a metric.
General aviation (US)

1 death in 64,000 hours
156x as dangerous as commercial aviation

Flying sailplanes (Germany, France)

1 death in 50,000 hours
200x as dangerous as commercial aviation

The following graph shows the relative difference between sailplanes and powered planes:

Charts and sources at this link.

It is hard to compare because of hours flown... I looked at glider accidents for the last 18 years. There are a lot of non fatal accidents. Fatal glider accidents (no particular order) seems to be in-flight break up, stalls and collision with ground (typically in mountainous terrain). Tow accidents resulting in stalls or loss of control is another critical phase of flight it seems. There are different tows like car, winch and of course tow plane. (I am not a glider pilot but ATP, CFI fixed wing.)
One thing gliders have going for them is the slow stall and sink rate. So even an off field landings should be survivable as the speeds are slow. On the other hand there is not a lot of structure around you. High performance gliders put the pilot stretched out in the very front of the air frame. Fiberglass or Carbon fiber does not bend and absorb impact, it reaches it's limit and ruptures. Aluminum airfares typical of powered fixed wings tend to bend and absorb some energy.

This is an interesting commentary but I don't feel that this (or the other answer) has answered the question yet. Which is safer?

winch, not wench, launches.

There was an air cadet that staĺled and spun a schwietzer 1-26 at my old club from 300 ft.  Stalling at 35 mph it basicaly went "bonk" onto the ground and he climbed out with a sore ankle.


text:
Why could increases in cockpit voice and image recording potentially raise privacy concerns?
A major concern someone or other brings up against practically every suggestion to broaden the uses of cockpit voice recordings or add cockpit image/video recorders to the mix (both of these, especially the latter, being actions that accident investigators have long urged regulatory agencies and aircraft operators to implement in the name of air safety, and which the regulators and the operators have, for just as long, worked to weasel out of), and one which dates right back to when CVRs were first introduced, is that doing so would supposedly be a violation of the pilots' privacy.1
This concern seems somewhat misplaced:

For pilots operating commercially (including those operating the vast majority of the flights that would fall under the aforementioned proposed recording-expansion mandates), the cockpit is their workplace and the aircraft an item of company equipment, and there has generally never been any expectation of privacy for workers in the workplace while on duty, especially not as regards the use of company-owned equipment.3
For general-aviation pilots, the only time when they would be required to turn the recorded data over to anyone would be following an accident or incident, when the pilot(s) would have little reason (and, depending on the nature of the occurrence, may have been definitively rendered unable) to object to handing the data over.

Where, then, is the justification for these alleged concerns?

1: Other excuses offered for not installing cockpit image recorders are the large amounts of oh-so-expensive storage required to record and store cockpit video (which most likely stopped being a valid concern in the early 1970s, with the advent of miniaturised videotape systems with recording lengths of up to an hour - twice the length of contemporary CVRs! - and is a frankly ridiculous argument to make nowadays, when a tebibyte of solid-state flash memory, enough for dozens to hundreds of hours of high-res cockpit video from multiple vantage points, can be had for less than a hundred bucks in a package the size of a candy bar2), and the supposed uselessness of recorded image data for accident-investigation purposes (a contention easily refuted by a cursory glance at the many accidents and incidents that have prompted accident investigators to repeatedly and consistently urge for the installation of CIRs, as well as by five minutes’ or so thought about all the things that could be useful to an accident investigation and which would show up on a video recording, but not - or, at least, not identifiably - on an audio recording).
2: In fact, the storage for a CIR would probably be less expensive than that in a consumer-grade SSD, as flight recorders, which record data in strict sequential order and where data recoverability is far more critical than data access control, would not use the complex encryption and wear-levelling circuitry found in most consumer flash devices.
3: This is why (for example) it is both legal and ubiquitous for companies to install software on their work computers to remotely monitor what their employees are doing on said computers.

I get where you are coming from. The argument can definitively be made for commercial operations. Not just for air carriers. I know of at least 1 external load helicopter operator that uses video recording extensively. The U.S. Helicopter Safety Team is promoting wider use. Not-for-hire pilots would be a hard sell. Especially in the US where freedom and privacy is of paramount importance for most. We have the technology to put such surveillance in cars as well. Americans would not like to have their personal spaces (house, car, plane) monitored. Even the spector of big brother would be fought

Your assumption about privacy expectations may not always be accurate. Depending on the country and the union agreement (if any), it's possible that employees may indeed have privacy protections in the workplace. There's a ton of employment law around workplace monitoring and if you don't get a good answer here you might consider asking in the law and/or workplace stacks about precedents for continuously recording everything that employees say, whether work-related or not.

"there has generally never been any expectation of privacy for workers in the workplace while on duty"—nobody likes working in a panopticon. Workers frequently want some degree of privacy, whether through an informal process ("if my boss insists on looking over my shoulder every damn minute I'm going to find another job") or though union negotiations. Workers do accept some trade-offs to their privacy, either because it's important for their job or because they have no other option, but workers with bargaining power often do consider privacy to be something worth bargaining for.

I'd note that one of your links discusses an example of an abuse of privacy with CVR systems, so it's not just a theoretical problem.

Good question! I though blackboxes records were only read in case of investigation triggered by incident or accident, in which case privacy is not a concern (every element can be meaningful, even the ambiance in the cockpit can bring element about CRM). Moreover, sterile cockpit rule implies no private exchange during the concerned flight phases.

Many ATC towers have "room recording" (not sure what the English term is). Essentially one or multiple microphones that continuously record everything that is said in the tower.

I suggest that you direct your question to people in an airline pilot's union. That is who understands the harm to their profession.

This is definitely an interesting question. However, I just can't see it as a StackExchange style of question. It's a topic for discussion on PPrune or another forum.

I will answer this question with the caveat that it is asking for an opinion, and therefore your experience may vary due to different regulatory authorities. I answer this question from an Australian CASA context but note that while there are differences between CASA, EASA and FAA, they operate so similar that in many cases the courseware I teach to students to become an engineer under those systems is almost identical. Therefore, I feel like I am able to make an informed opinion on the matter even though the courseware I teach is primarily designed for a CASA context. Having said that, If your aviation regulatory authority is not based under those I have just mentioned, I have no idea. Go consult their regulations if that is the case.
I will now paraphrase from an avionics textbook on module 13 (avionics instruments other - Cockpit Voice Recorder system) under the CASA part 66 licence outcomes:
-It is an offence under the Air Navigation Act 1920 to disclose any information on a cockpit voice recorder for the purposes other than that listed in part 2A of this act. This means that unless it is directly related to the investigation of an accident it will not be made public.
-CVR recordings may not be used as evidence in any criminal or civil proceedings within Australia
-CVR recordings cannot be used as grounds for any disciplinary action by employers
-It is an offence to make public any CVR recording. Large fines apply
-Only the investigative authority in the course of investigation or court order is to disclose the recording for the express purpose that it is relevant to understanding the cause of an accident
My text goes on to mention things like if the recording is distressing then a transcript should be made and the original recording not played if it does not add anything to the investigation.
My textbook does not specifically mention video recording systems but I would say they fall under the definition in the Air Navigation Act 1920 and therefore treated the same. But this is something lawyers can fight over.
To some up then, due to the points raised above, I feel like there are no grounds to feel concerned about your privacy if there were increases in recording. This is due to the protection given for your personal data under the act. Each nation should have a similar act that protects people in a similar way. If it doesn't, I would hope your workers union could lobby for change. There are no downsides I can see to increasing recording time and increasing the use of video in the name of safety, especially where a rigid protocol of non-disclosure exists in the form of appropriate legislation. Privacy concerns can only exist in a world where you are not confident in the system providing the protections.
I will finish by adding another opinion on the subject. The only time I wouldn't recommend increasing recording is on very light airframes where space and weight is an issue. There is an ongoing trend in the last 40 years or more and more flight parameters being recorded under the regs, so it makes sense to also find new and innovative ways to record video and voice in the cockpit as well.